OSIRIS-REx: Chemical and structural analysis of asteroidal material returned from C-type asteroid Bennu.

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This proposal is a follow-up of our very successful study of asteroidal samples from Ryugu in the framework of JAXAs Hayabusa2 mission. The elongation of the study of asteroidal samples is embedded within the sample return mission OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer) (NASA), whose mission target is the investigation of the carbonaceous C-class near-Earth asteroid Bennu. In the proposed project we will work in the framework of the OSIRIS-REx mission in the mineralogy and petrology working group (MAPWG) preliminary investigation team applying synchrotron radiation XRF and TEM analyses. The two most primary objectives of the OSIRIS-REx mission are: 1) to “return and analyze a sample of pristine carbonaceous asteroid regolith in an amount sufficient to study the nature, history, and distribution of its constituent minerals and organic material”; and 2) to “map the global properties, chemistry, and mineralogy of a primitive carbonaceous asteroid to characterize its geologic and dynamic history and provide context for the returned samples”. The goal is to acquire new and fundamental information about the relationship between the terrestrial planets and the small-body populations, the origins of the Earth and the source of the Earth’s organic materials and water. Thought to be minimally altered since the formation of the Solar System, carbonaceous asteroids may provide insight into whether these materials were present in the terrestrial planet region during the earliest planet formation era, or delivered to the Earth by a late phase of bombardment. Sample material was directly collected from the asteroid Bennu´s surface in 2020 and is currently being carried back to Earth on board the OSIRIS-REx spacecraft, due to arrive on the 24th September 2023. Upon arrival, this directly harvested asteroidal material will be transported to the OSIRIS-REx curation facility at the Johnson Space Centre (JSC), weighed, sorted and curated. Some of the material will then be distributed to the primary investigating teams, an international and interdisciplinary group of expert subteams, for specific targeted analysis. As one of the designated expert teams of the OSIRIS-REx mission, we will be involved in the initial analysis stage of the project and will be one of the first teams to receive some of the Bennu material. In our investigation of the Bennu material, we will obtain chemical, mineralogical and petrological data that will help decipher the hydrous, thermal and shock history of Bennu, with the application of two separate analytical methods, namely synchrotron-XRF and TEM.